While it's usually Erin, Orla and the rest of the Derry Girls gang who are the focus of each episode, Mary (Tara Lynne O'Neill) and Aunt Sarah (Kathy Kiera Clarke) are taking over for season 3's penultimate outing, with creator Lisa McGee confirming that episode 5 will flashback to their school days.
Speaking to Digital Spy, Lisa McGee said that next week's instalment would be dedicated to the Derry Girls' parents, with the episode focusing on the "horrific" times younger Mary (Shauna Higgins) and Sarah (Dearbhaile McKinney) grew up in back in the '70s.
"Writing this show, honestly – and this might sound a bit sentimental – it's been a real learning experience for me as a person, not just a writer," she said. "I don't talk about a lot of the terrible things.
"In Northern Ireland, you handle it with humour and you just crack on. I think for the parents' generation, it was a war zone. It was horrific what they went through, and we just didn't appreciate it."
She continued: "By writing the show and looking back, I realised why they were so strict, why the school was so strict, what they had seen, what they lived through, and I have such an appreciation and respect.
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"I'm so embarrassed at how we behaved now! They were incredible what they got through, they're just the strongest people, that generation."
The episode will see Ma Mary and Aunt Sarah get ready for their 'Class of '77' school reunion, with Channel 4 hinting that a long-held secret about that night 20 years prior could come to light.
While there are just three more episodes to go in the Channel 4 comedy's final season, Derry Girls thankfully announced last week that it would be ending with a special bonus episode after the season 3 finale.
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